The present invention relates to an automatic transmission drive apparatus for a vehicle, comprising an oil-pressure output device, such as an electric pump unit, which is attached to an automatic transmission from outside.
Conventionally, an idling stop system which controls an engine to automatically stop when a specified stop condition of a vehicle is satisfied and to restart when a specified restart condition of the vehicle is satisfied for improvement of fuel economy and reduce of emission, is known (see Japanese Patent Laid-Open Publication No. 2000-313253, for example).
In the vehicle equipped with the idling stop system, an oil pump generally stops during an engine stop, so that an oil pressure may not be supplied to frictional engaging elements of an automatic transmission from the oil pump. Accordingly, when the vehicle stops in a state in which a gear shift range of the automatic transmission is set at a drive range, for example, a specified frictional engaging element to be engaged may be released improperly.
In contrast, there has been proposed an electric pump unit which is attached to an automatic transmission from outside in addition to the above-described oil pump driven by the engine, in which a necessary oil pressure to engage the frictional engaging element can be supplied by this electric pump unit during the engine stop (see Japanese Patent Laid-Open Publication No. 2005-098338, for example). Herein, the electric pump unit is arranged around a torque converter housing of the automatic transmission at a specified position which is at a front and lower portion of the torque converter housing. Thus, a layout change around the automatic transmission may be unnecessary between a case of installing the idling stop system (with the electric pump unit) and another case of not installing the idling stop system (without the electric pump unit).
However, in case the electric pump unit is arranged at the front portion of the torque converter housing, like the above-described conventional example, there is a problem in that a support structure would become complex in order to properly reduce an influence on a vehicle crash performance.